An association between cystatin C and heart failure, particularly diastolic heart failure, is not unexpected given that it is a sensitive and specific marker of renal insufficiency and highly correlates with hypertension [9]; however, various lines of evidence suggest that the relationship between cystatin C and LV mass and hypertrophy may go beyond simple confounding due to its association with hypertension [11]. This evidence concerns the gene CST3 and heart failure.